Spectacle lens design system, supply system, design method and manufacturing method

ABSTRACT

A spectacle lens design system, including: an eyeball rotation center determination means that identifies an corneal apex position of an eye of a subject based on an image photographed by a predetermined photographing apparatus and determines an eyeball rotation center position of the subject based on the identified corneal apex position; a visual line information calculation means that calculates visual line information of the subjected defined when the subject watches a visual target disposed at a predetermined position, based on the eyeball rotation center position determined by the eyeball rotation center determination means and the position of the visual target; and a shape design means that designs a shape of a spectacle lens based on predetermined prescription information and the visual line information calculated by the visual line information calculation means.

TECHNICAL FIELD

The present invention relates a method for designing and manufacturingspectacle lenses using visual line information of a subject.

BACKGROUND ART

Recently, introducing visual line information of a scheduled wearer intodesign of spectacle lenses has been proposed in order to providespectacle lenses more suitable for a customer (a scheduled wearer or asubject). A specific design method for such spectacle lenses isdescribed, for example, in Japanese Patent Publication No. 4942661B(hereafter, referred to as patent document 1).

However, the design method described in patent document 1 is based onthe premise that a scheduled wearer is supposed to wear spectacle lenseswhen measurement of visual lines is performed. Therefore, a problem thatthe design method is not able to support a scheduled wearer of nakedeyes is pointed out.

SUMMARY OF THE INVENTION

Non-patent document 1 (Kenneth Alberto Funes Mora and Jean-Marc Odobez:“Gaze Estimation from Multimodal Kinetic Data” p. 4321-4326) describestechnology where a subject and a visual target are photographed using anRGB-D camera capable of obtaining an RGB image and a distance image(depth information) and visual lines of the subject viewing the visualtarget are measured based on the photographed images. According to themethod described in the non-patent document 1, the subject is in a nakedeye condition when the measurement of the visual lines is performed.

For this reason, the inventor of the present invention has come up withan idea that, by introducing the measurement technology for visual linesdescribed in the non-patent document 1 into design of spectacle lenses,it becomes possible to provide spectacle lenses having the aberrationdistribution suitable for movement of the visual lines regardless ofwhether or not a scheduled wearer is in a naked eye condition, and theinventor has made intensive studies. As a result, the inventor has foundthat it is impossible to simply introduce the measurement technology forvisual lines described in the non-patent document 1 into design ofspectacle lenses. Specifically, when spectacle lenses are designed usingvisual line information measured by the measurement technology forvisual lines described in the non-patent document 1, if simulation inwhich a scheduled wearer performs near vision (e.g., reading) in a stateof wearing spectacle lenses is executed, blur, shaking or distortionoccurs. Therefore, it is found that aberration distribution suitable forvisual lines for near vision is not achieved.

The present invention is made considering the above describedcircumstances. That is, the object of the present invention is toprovide a design system, a supply system, a design method and amanufacturing method for spectacle lenses having aberration distributionsuitable for each visual line distance.

A spectacle lens design system according to an embodiment of theinvention comprises: an eyeball rotation center determination means thatidentifies an corneal apex position of an eye of a subject based on animage photographed by a predetermined photographing apparatus anddetermines an eyeball rotation center position of the subject based onthe identified corneal apex position; a visual line informationcalculation means that calculates visual line information of thesubjected defined when the subject watches a visual target disposed at apredetermined position, based on the eyeball rotation center positiondetermined by the eyeball rotation center determination means and theposition of the visual target; and a shape design means that designs ashape of a spectacle lens based on predetermined prescriptioninformation and the visual line information calculated by the visualline information calculation means.

It is considered that one of factors which cause, particularly duringnear vision, blur, shake, distortion and the like on the spectacle lensdesigned using visual line information measured by visual linemeasurement technology described in non-patent document 1 is the factthat a start point (a corneal apex) of the visual line information isdifferent from an origin (the eyeball rotation center) defined in designof the spectacle lens. For this reason, in the embodiment of theinvention, the visual line information is calculated while setting thestart point of the visual line information at the eyeball rotationcenter which is equal to the origin defined in the design of thespectacle lens. By designing the spectacle lens using such visual lineinformation, it is possible to prevent occurrence of an error of adirection and a distance of a visual line caused by the differencebetween the start point of the visual line information and the origindefined in design of the spectacle lens. That is, according to theembodiment of the invention, by using the above described visual lineinformation, the spectacle lens having the aberration distributionsuitable for each visual line information can be designed.

The spectacle lens design system may further comprise a wearingparameter calculation means that calculates a wearing parameter based onthe corneal apex position identified based on the image photographed bythe predetermined photographing apparatus. In this case, the shapedesign means designs the shape of the spectacle lens using the wearingparameter calculated by the wearing parameter calculation means.

The wearing parameter may include at least one of a frame pantoscopicangle, a frame face form angle, a frame vertex distance, a pupillarydistance and a near working distance.

The wearing parameter calculation means may continuously calculate thewearing parameter as time series data, and determines a true wearingparameter by using values calculated continuously as the time seriesdata.

When a coordinate system whose origin is equal to a reference point setat the predetermined photographing apparatus is defined as aphotographing apparatus coordinate system, and a coordinate system whoseorigin is equal to a reference point set at a head of the subject isdefined as a head coordinate system, the eyeball rotation centerdetermination means may operate to: calculate a position and a pose ofthe head of the subject in the photographing apparatus coordinate systembased on the image photographed by the predetermined photographingapparatus; define the head coordinate system based on the calculatedposition and the pose of the head of the subject; convert a coordinateof the corneal apex position in the photographing apparatus coordinatesystem to the corneal apex position in the head coordinate system bymaking directions of coordinate axes of the defined head coordinatesystem and directions of coordinate axes of the defined photographingapparatus coordinate system coincide with each other by performingpredetermined coordinate conversion; and obtain a coordinate of aposition of the eyeball rotation center by adding a default value to thecoordinate of the corneal apex position in the converted head coordinatesystem.

The spectacle lens design system may further comprise: a detection meansthat detects, at predetermined time intervals, the position and the poseof the head based on the image photographed by the predeterminedphotographing apparatus or detected data by a detecting apparatuscapable of detecting the position and the pose of the head of thesubject; and a pseudo moving means that moves, at predetermined timeintervals, the position of the visual target, in a pseudo manner, by anamount corresponding to a difference of the position of the head beforeand after detection by the detection means and a difference of the poseof the head before and after detection by the detection means so thatthe position and the pose of the head of the subject is maintained, in apseudo manner, before and after the detection. In this case, the visualline information calculation means may calculate the visual lineinformation based on the determined eyeball rotation center position andthe position of the visual target moved in a pseudo manner.

The image may be photographed by the predetermined photographingapparatus at a predetermined frame rate, and in the eyeball rotationcenter determination means, tentative positions of the eyeball rotationcenter may be calculated for a predetermined number of frame images bydetermining eyeball rotation center positions for a predetermined numberof frames, and a true eyeball rotation center position may be determinedbased on the calculated tentative positions in the predetermined numberof frame images.

The visual line information may be vector information of a visual lineincluding a vector length and a unit vector of a visual line connectingthe eyeball rotation center position with the position of the visualtarget.

The visual line information further may include time axis information ofthe visual line. The spectacle lens design system may further comprise:a tentative shape design means that designs a tentative shape of thespectacle lens based on predetermined prescription information; a usecalculation means that calculates a position on a spectacle lens throughwhich a visual line defined when the subject wears a spectacle lenshaving the tentative shape passes, and a staying time of the visual lineat the calculated position on the spectacle lens, based on the vectorlength, the unit vector and the time axis information of the visual lineincluded in the visual line information calculated by the visual lineinformation calculation means, and thereby calculates a use region and ause frequency in the spectacle lens by the subject; and a correctionmeans that corrects the tentative shape based on the calculated useregion and the use frequency.

The spectacle lens design system may further comprise a visual lineinformation displaying means that displays information concerning thecalculated visual line information.

A spectacle lens supply system according to an embodiment of theinvention comprises: one of the above described spectacle lens designsystems; and a spectacle lens manufacturing apparatus that manufacturesspectacle lenses using design data by the spectacle lens design system.

A spectacle lens design method according to an embodiment of theinvention, comprises: a photographing step of photographing a subjectwith a predetermined photographing apparatus; a determination step ofidentifying an corneal apex position of an eye of the subject based onan image photographed by the photographing step and determining aneyeball rotation center position of the subject based on the identifiedcorneal apex position; a calculation step of calculating visual lineinformation of the subjected defined when the subject watches a visualtarget disposed at a predetermined position, based on the eyeballrotation center position determined by the determination step and theposition of the visual target; and a shape design step of designing ashape of a spectacle lens based on predetermined prescriptioninformation and the visual line information calculated by thecalculation step.

In the embodiment of the invention, the visual line information iscalculated while setting the start point of the visual line informationat the eyeball rotation center which is equal to the origin defined inthe design of the spectacle lens. By designing the spectacle lens usingsuch visual line information, it is possible to prevent occurrence of anerror of a direction and a distance of a visual line caused by thedifference between the start point of the visual line information andthe origin defined in design of the spectacle lens. That is, accordingto the embodiment of the invention, by using the above described visualline information, the spectacle lens having the aberration distributionsuitable for each visual line information can be designed.

The spectacle lens design method may further comprise a wearingparameter calculation step of calculating a wearing parameter based onthe corneal apex position identified based on the image photographed bythe predetermined photographing apparatus. In this case, in the shapedesign step, the shape of the spectacle lens may be designed using thecalculated wearing parameter.

The wearing parameter may include at least one of a frame pantoscopicangle, a frame face form angle, a frame vertex distance, a pupillarydistance and a near working distance.

In the wearing parameter calculation step, the wearing parameter iscontinuously calculated as time series data, and a true wearingparameter is determined by using values calculated continuously as thetime series data.

In the spectacle lens design method, when a coordinate system whoseorigin is equal to a reference point set at the predeterminedphotographing apparatus is defined as a photographing apparatuscoordinate system, and a coordinate system whose origin is equal to areference point set at a head of the subject is defined as a headcoordinate system, in the determining step a position and a pose of thehead of the subject in the photographing apparatus coordinate system maybe calculated based on the image photographed by the predeterminedphotographing apparatus; the head coordinate system may be defined basedon the calculated position and the pose of the head of the subject; acoordinate of the corneal apex position in the photographing apparatuscoordinate system may be converted to the corneal apex position in thehead coordinate system by making directions of coordinate axes of thedefined head coordinate system and directions of coordinate axes of thedefined photographing apparatus coordinate system coincide with eachother by predetermined coordinate conversion; and a coordinate of aposition of the eyeball rotation center may be obtained by adding adefault value to the coordinate of the corneal apex position in theconverted head coordinate system.

The design method may perform a detection step of repeatedly detectingthe position and the pose of the head based on the image photographed bythe predetermined photographing apparatus or detected data by adetecting apparatus capable of detecting the position and the pose ofthe head of the subject; and a pseudo moving step of repeatedly moving,in a pseudo manner, the position of the visual target by an amountcorresponding to a difference of the position of the head before andafter detection by the detection means and a difference of the pose ofthe head before and after detection. In this case, in the calculationstep the visual line information may be calculated based on the eyeballrotation center position determined in the determination step and theposition of the visual target moved in a pseudo manner by the pseudomoving step.

In the photographing step, the image may be photographed at apredetermined frame rate. In this case, tentative positions of theeyeball rotation center may be calculated for a predetermined number offrame images by executing the determination step for a predeterminednumber of frames, and a true eyeball rotation center position may bedetermined based on the calculated tentative positions in thepredetermined number of frame images.

The visual line information is, for example, vector information of avisual line including a vector length and a unit vector of a visual lineconnecting the eyeball rotation center position with the position of thevisual target.

The visual line information further may include time axis information ofthe visual line.

The spectacle lens design method according to an embodiment of theinvention further comprise: a tentative shape design step of designing atentative shape of the spectacle lens based on predeterminedprescription information; a use calculation step of calculating aposition on a spectacle lens through which a visual line defined whenthe subject wears a spectacle lens having the tentative shape passes,and a staying time of the visual line at the calculated position on thespectacle lens, based on the vector length, the unit vector and the timeaxis information of the visual line included in the visual lineinformation calculated by the calculation step, and thereby calculatinga use region and a use frequency in the spectacle lens by the subject;and a correction step of correcting the tentative shape based on thecalculated use region and the use frequency.

The spectacle lens design method may further comprise a visual lineinformation displaying step of displaying information concerning thecalculated visual line information.

A spectacle lens manufacturing method according to an embodiment of theinvention comprises a spectacle lens manufacturing process ofmanufacturing the spectacle lens designed by the above described method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a spectaclelens manufacturing system according to an embodiment of the invention.

FIG. 2 is a flowchart illustrating a manufacturing process for spectaclelenses according to the embodiment of the invention.

FIG. 3 is a block diagram illustrating a configuration of a visual lineinformation collecting apparatus according to an example 1 of theinvention.

FIG. 4 illustrates a use condition of the visual line informationcollecting apparatus according to the example 1 of the invention.

FIG. 5 is a flowchart illustrating a visual line information collectingprocess according to the example 1 of the invention.

FIG. 6 is a flowchart illustrating step S12 (calculation process ofeyeball rotation center coordinate) in FIG. 5,

FIG. 7 illustrates an example of an eyeball model.

FIG. 8 illustrates a coordinate system of an RGB-D camera and acoordinate system of a head of a scheduled wearer according to theexample 1 of the invention.

FIG. 9 is a flowchart illustrating step S3 (calculation process forvisual target coordinate) in FIG. 5.

FIG. 10 illustrates an example of a time chart showing asynchronousphotographing timing of two RGB-D cameras.

FIG. 11 is a block diagram illustrating a configuration of a visual lineinformation collecting apparatus according to an example 2 of theinvention.

FIG. 12 illustrates a use condition of the visual line informationcollecting apparatus according to the example 2 of the invention.

FIG. 13 is a flowchart illustrating a visual line information collectingprocess according to the example 2 of the invention.

FIG. 14 illustrates a use condition of a visual line informationcollecting apparatus according to an example 3 of the invention.

FIG. 15 is a flowchart illustrating a visual line information andwearing parameter collecting process by the visual line informationcollecting apparatus according to the example 3 of the invention.

FIG. 16 is a flowchart illustrating a frame pantoscopic anglecalculation process according to the example 3 of the invention.

FIG. 17 is a transversal cross sectional view of a frontal face threedimensional data, and is used for explaining the frame pantoscopic anglecalculation process.

FIG. 18 is a flowchart illustrating a frame face than angle calculationprocess according to the example 3 of the invention.

FIG. 19 is a top cross sectional view of the frontal face threedimensional data, and is used for explaining the frame face form anglecalculation process.

FIG. 20 is a flowchart illustrating a frame vertex distance calculationprocess according to the example 3 of the invention.

FIG. 21 is a transversal cross sectional view of the frontal face threedimensional data, and is used for explaining the frame vertex distancecalculation process.

FIG. 22 is a front view of the frontal face three dimensional data, andis used for explaining a pupillary distance calculation process.

FIG. 23 is a flowchart illustrating a progressive lens design process bya spectacle lens design computer.

FIG. 24 illustrates an example of a virtual model constructed by thespectacle lens design computer.

FIG. 25 illustrates astigmatism distribution before and afteroptimization according to a design example 1.

FIG. 26 shows distribution of logMAR visual acuity before and afteroptimization according to a design example 2.

FIG. 27 is an explanatory illustration for explaining a state of avisual line in a design example 3-1.

FIG. 28 is a graph illustrating average transmission dioptric power inthe design example 3-1.

FIG. 29 is an explanatory illustration for explaining a state ofpupillary distance PD in a design example 3-2.

FIG. 30 is a graph illustrating a difference in transmission astigmatismbetween conventional design and the design example 3-2.

FIG. 31 is an explanatory illustration for explaining a position of aneye point, a visual line passing position and a state of addition powerin a design example 3-3.

FIG. 32 is a graph illustrating an addition power curve according to adesign example 4-1 and an addition power curve according to conventionaldesign.

FIG. 33 illustrates transmission astigmatism in the design example 4-1and transmission astigmatism in conventional design.

FIG. 34 is a graph illustrating a difference in transmission astigmatismbetween the design example 4-1 and conventional design.

FIG. 35 is a graph illustrating an addition power curve in a designexample 4-2 and an addition power curve in conventional design.

FIG. 36 illustrates transmission astigmatism in the design example 4-2and transmission astigmatism in conventional design.

FIG. 37 is a graph illustrating a difference in transmission astigmatismbetween the design example 4-2 and conventional design.

FIG. 38 is a flowchart illustrating a design process for a single-visionlens by the spectacle lens design computer.

FIG. 39 illustrates an example an image in which a design result, aframe and visual line information are arranged to overlap with eachother.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

In the following, a spectacle lens manufacturing system (a spectaclelens supply system) according to an embodiment of the invention isdescribed with reference to the accompanying drawings.

Spectacle Lens Manufacturing System 1

FIG. 1 is a block diagram illustrating a configuration of a spectaclelens manufacturing system 1 according to the embodiment. As shown inFIG. 1, the spectacle lens manufacturing system 1 includes an opticalstore 10 which orders spectacle lenses according to a prescription for acustomer (a scheduled wearer or a subject), and a spectacle lensmanufacturing factory 20 which manufactures spectacle lenses afterreceiving the order from the optical store 10. The order to thespectacle lens manufacturing factory 20 is issued through apredetermined network, such as the Internet, or data transmission by,for example, facsimile. Orderers may include ophthalmologists or generalconsumers.

Optical Store 10

In the optical store 10, a store computer 100 and a visual lineinformation collecting apparatus 150 are installed. The store computer100 is, for example, a general PC (Personal Computer), and software forordering spectacle lenses to the spectacle lens manufacturing factory 20has been installed in the store computer 100. To the store computer 100,lens data and frame data are input through an operation to a mouse or akeyboard by an optical store staff. Further, to the store computer 100,the visual line information collecting apparatus 150 is connected via anetwork, such as a LAN (Local Area Network), or a serial cable, andvisual line information of a scheduled wearer collected by the visualline information collecting apparatus 150 is input to the store computer100. The lens data includes, for example, visual line informationcollected by the visual line information collecting apparatus 150, aprescription (e.g., spherical power, cylindrical power, a cylindricalaxis direction, prismatic power, prism base setting, an addition powerand PD (Pupillary Distance) and the like), lens material, a refractiveindex, the type of optical design, a lens outer diameter, a lensthickness, a peripheral part thickness, decentering, a base curve, awearing condition of spectacle lenses (a corneal vertex distance, a lenspantoscopic angle, a lens face form angle), the type of spectacle lens(a single-vision spherical lens, a single-vision aspherical lens, amultifocal lens (a bifocal lens or a progressive power lens)), coating(dyeing processing, hard coating, anti-reflection coating, ultravioletlight cutting and the like), and layout data according to a customer'srequest. The frame data includes shape data of a frame selected by acustomer. The frame data is managed, for example, by barcode tags, andcan be obtained by reading a barcode tag adhered to a frame by a barcodereader. The store computer 100 transmits the ordering data (the lensdata and the frame data) to the spectacle lens manufacturing factory 20via, for example, the Internet.

Spectacle Lens Manufacturing Factory 20

In the spectacle lens manufacturing factory 20, a LAN (Local AreaNetwork) centering at a host computer 200 to which various terminaldevices including a spectacle lens design computer 202 and a spectaclelens processing computer 204 are connected is constructed. Each of thespectacle lens design computer 202 and the spectacle lens processingcomputer 204 is a general PC. On the spectacle lens design computer 202and the spectacle lens processing computer 204, a program for spectaclelens design and a program for spectacle lens processing are installed,respectively. To the host computer 200, the ordering data transmittedvia the Internet is input from the store computer 100. The host computer200 transmits the ordering data input thereto to the spectacle lensdesign computer 202.

Manufacturing of Spectacle Lenses in Spectacle Lens ManufacturingFactory 20

S1 in FIG. 2 (Design of Spectacle Lens)

FIG. 2 is a flowchart illustrating a manufacturing process for spectaclelenses in the spectacle lens manufacturing factory 20. In the spectaclelens design computer 202, a program for designing spectacle lenses inresponse to received order has been installed, and the spectacle lensdesign computer 202 creates design data and edge processing data basedon ordering data. Design of spectacle lenses using the spectacle lensdesign computer 202 is explained in detail later. The spectacle lensdesign computer 202 transfers the created lens design data and the edgeprocessing data to the spectacle lens processing computer 204.

S2 in FIG. 2 (Manufacturing of Spectacle Lens)

The spectacle lens processing computer 204 reads the lens design dataand the edge processing data transferred from the spectacle lens designcomputer 202, and drives and controls a processing machine 206.

Let us consider, for example, a case where a plastic spectacle lens ismanufactured by a cast polymerization method. In this case, theprocessing machine 206 makes molding dies respectively corresponding toan outer surface (a convex surface) and an inner surface (a concavesurface) of a lens by grinding and polishing material, such as metal,glass or ceramics, in accordance with the lens design data. The pair ofmolding dies thus made is disposed to face with each other at aninterval corresponding to the thickness of the spectacle lens, and anadhesive tape is wound around an outer circumferential surface of theboth molding dies so that the interval between the both molding dies issealed. When the pair of molding dies is set on a spectacle lens moldingapparatus 208, a hole is opened in a part of the adhesive tape, and lensmaterial liquid is injected into a cavity (a sealed space between theboth molding dies) through the hole. The lens material liquid injectedand filled into the cavity is then polymerized and cured by heat orultraviolet irradiation. As a result, a polymer (a lens base material)to which a peripheral shape defined by transfer surface shapes of thepair of molding dies and the adhesive tape has been transferred isobtained. The lens base material obtained by the cast polymerizationmethod is then removed from the molding dies. The removed lens basematerial is then subjected to removal of residual stress by an annealingprocess, and various coatings, such as, dyeing processing, hard coating,anti-reflection coating and ultraviolet light cutting. Thus, spectaclelenses are completed and are delivered to the optical store 10.

In order to enhance productivity, in the spectacle lens manufacturingfactory 20, the whole production range of dioptric powers is dividedinto a plurality of groups, and semi-finished lens blank groups havingconvex surface curve shapes (e.g., a spherical shape or an asphericalshape) and lens diameters complying with respective production rangesare prepared in advance in preparation for orders. The semi-finishedlens blank is, for example, a resin blank or a glass blank of whichconvex and concave surfaces are an optical surface (a finished surface)and a non-optical surface (an unfinished surface), respectively. In thiscase, an optimum semi-finished lens blank is selected based on the lensdata, and the selected semi-finished lens blank is set on the processingmachine 206. The processing machine 206 grinds and polishes the concavesurface of the semi-finished lens blank set on the processing machine206, so as to make an uncut lens. The uncut lens of which concavesurface shape has been made is then subjected to various coatings, suchas, dyeing processing, hard coating, anti-reflection coating andultraviolet light cutting. The outer circumferential surface of theuncut lens after being subjected to the various coatings is thensubjected to the peripheral processing based on the edge processingdata. The spectacle lenses processed into circular shapes are thendelivered to the optical store 10.

Method for Collecting Visual Line Information by Visual Line InformationCollecting Apparatus 150

As described above, it is found through studies made by the inventor ofthe present invention that, when spectacle lenses are designed usingvisual line information measured by the measurement technology forvisual lines described in the non-patent document 1, if simulation inwhich a scheduled wearer performs near vision (e.g., reading) in a stateof wearing spectacle lenses is executed, blur, shaking or distortionoccurs, and therefore, it is found that aberration distribution suitablefor visual lines for near vision is not achieved. It is appropriate toset a start point of a visual line at an eyeball rotation center becausein general a spectacle lens is designed by defining the eyeball rotationcenter as an origin. On the other hand, in the technology for measuringa visual line described in the non-patent document 1, a corneal apex isset as a start point of a visual line. When a visual target (an endpoint of a visual line) is at a distant position (i.e., in the case of adistance vision), an effect on design of a spectacle lens caused by ashift of a direction and a distance of the visual line resulting fromthe difference of the start points is small. However, when a visualtarget (an end point of a visual line) is at a near position (i.e., inthe case of a near vision), an effect of on design of a spectacle lenscaused by a shift of a direction and a distance of the visual lineresulting from the difference of start points is large. It is consideredthat one of factors of not being able to obtain aberration distributionsuitable for the visual line for the near vision when the spectacle lensis designed while introducing the technology for measuring the visualline described in the non-patent document 1 is the fact that the cornealapex is set as the start point of the visual line. Therefore, in thefollowing, three examples (example 1 to 3) regarding a visual lineinformation collecting process for collecting visual line information ofa scheduled wearer suitable for designing and manufacturing a spectaclelens having aberration distribution suitable for every visual linedistance ranging from a near point to a distant point are explained.

Example 1 Configuration of Visual Line Information Collecting Apparatus150

FIG. 3 is a block diagram illustrating a configuration of the visualline information collecting apparatus 150 according to the example 1. Asshown in FIG. 3, the visual line information collecting apparatus 150according to the example 1 includes an information processing terminal152, and RGB-D cameras 154-1 and 154-2.

The information processing terminal 152 is a terminal, such as a desktopPC (Personal Computer), a laptop PC, a notebook PC, a tablet PC, or asmart phone, and includes a processor 152 a, a memory 152 b, a userinterface 152 c and a monitor 152 d. The processor 152 a totallycontrols components in the visual line information collecting apparatus150. The processor 152 a operates to collect visual line information ofa scheduled wearer by executing various programs stored in the memory152 b. The user interface 152 c is an input device, such as a mouse anda keyboard. The optical store staff is able to operate the visual lineinformation collecting apparatus 150 via the user interface 152 c. Forexample, a GUI (Graphical User Interface) required for collecting thevisual line information of a scheduled wearer by the visual lineinformation collecting apparatus 150 is displayed on the monitor 152 d.

Each of the RGB-D cameras 154-1 and 154-2 includes a camera 154 a and adistance image photographing unit 154 b. The camera 154 a is a digitalcamera capable of photographing a two-dimensional RGB image of asubject. The distance image photographing unit 154 b is a sensor capableof photographing a distance image. The distance image is a twodimensional image in which each of pixels constituting the image hasinformation regarding a depth direction (i.e., distance informationregarding the subject). Each of pixels constituting the distance imagehas correspondence with each of pixels constituting the RGB image by thecamera 154 a. It should be noted that the RGB-D camera itself is known,and can be seen, for example, in the non-patent document 1.

The processor 152 a is able to generate a subject image having threedimensional information by calculating three dimensional coordinate dataof each corresponding pixel in the RGB image by the camera 154 a basedon the depth information (the distance image) of each pixel constitutingthe distance image inputted from the distance image photographing unit154 b. In this example, by utilizing and improving the three dimensionalimage generating function, collection of the visual line information bythe visual line information collecting apparatus 150 is made possible.

FIG. 4 illustrates a use condition of the visual line informationcollecting apparatus 150 according to the example 1. FIG. 5 is aflowchart illustrating a visual line information collecting process bythe visual line information collecting apparatus 150 used in the usecondition shown in FIG. 4. As shown in FIG. 4, the RGB-D camera 154-1 isinstalled on a table. In the example shown in FIG. 4, a scheduled wearerS sits on a chair placed close to the RGB-D camera 154-1, and isinstructed to watch the RGB-D camera 154-1 side. In addition, at aposition further from the RGB-D camera 154-1 viewed from the scheduledwearer S and on the rear side of the RGB-D camera 154-1, a table isinstalled. On the table placed on the rear side of the RGB-D camera154-1, the RGB-D camera 154-2 is installed. In order that the relativeposition between the scheduled wearer S and the RGB-D cameras 154-1 and154-2 is made adjustable, the position, the height of a seating surfaceof the chair, and the position and the height of a top board of eachtable are made adjustable.

Visual Line Information Collecting Process by Visual Line InformationCollecting Apparatus 150

S11 in FIG. 5 (Photographing Process by RGB-D Camera)

The RGB-D camera 154-1 photographs an RGB image and a distance image ofthe scheduled wearer S at a predetermined frame rate. The RGB-D camera154-2 also photographs an RGB image and a distance image of a visualtarget O at a predetermined frame rate and at the timing synchronizedwith the RGB-D camera 154-1.

S12 in FIG. 5 (Calculation Process of Eyeball Rotation CenterCoordinate)

The processor 152 a calculates a coordinate ν_(rc1) of the eyeballrotation center which is a start point of a visual line of the scheduledwearer S. Broadly speaking, in step S12, a tentative value of theeyeball rotation center coordinate ν_(rc1) is calculated (steps S12 a toS12 g in FIG. 6 described later) for each of the frames photographed bythe RGB-D camera 154-1 in step S11 (photographing process by RGB-Dcamera) in FIG. 5. When a sufficient number of tentative values forobtaining statistics are obtained, an average value of the tentativevalues is determined as a definitive value (the definitive value isdefined as a true eyeball rotation center) of the eyeball rotationcenter coordinate ν_(rc1) (steps S12 h and S12 i in FIG. 6 describedlater). It is desirable that the scheduled wearer S pays attention tothe followings for calculation of the eyeball rotation center coordinateν_(rc1).

-   Face directly forward against the RGB-D camera 154-1 to photograph    both eyes.-   Do not move the head during the photographing.-   Remove Spectacle lenses if the scheduled wearer wears the spectacle    lenses in order to enhance the detection accuracy of the corneal    apex of each eye.

FIG. 6 is a flowchart illustrating in detail step S12.

Step S12 a in FIG. 6

The processor 152 a obtains the RGB image and the distance imagephotographed by the RGB-D camera 154-1 in step S11 (photographingprocess by RGB-D camera) in FIG. 5.

Step S12 b in FIG. 6

The processor 152 a detects an area of an eye of the scheduled wearer Sin the RGB image by analyzing the RGB image obtained by the RGB-D camera154-1. For example, by using the know technique described in non-patentdocument 2 (Paul Viola and Michel J. Jones: “Robust Real-Time FaceDetection”, International Journal of Computer Vision 57(2), pp. 137-154,(2004)), the area of the eye of the scheduled wearer S can be detected.

Step S12 c in FIG. 6

The processor 152 a identifies a coordinate of the corneal apex in theRGB image by regarding the corneal apex as lying at the center of thearea of the eye detected in step S12 b in FIG. 6. That is, a pixelpositioned at the center of the area of the eye detected in step S12 bin FIG. 6 is regarded as a pixel on which the corneal apex isphotographed.

Step S12 d in FIG. 6

The processor 152 a identifies a pixel in the distance imagecorresponding to the pixel (the coordinate of the corneal apex in theRGB mage) identified in step S12 c in FIG. 6. As a result, the threedimensional coordinate (x_(c), y_(c), z_(c)) of the corneal apex isobtained.

Step S12 e in FIG. 6

By using a known eyeball model, the three dimensional coordinate ν_(rc1)of the eyeball rotation center is calculated from the corneal apexcoordinate (x_(c), y_(c), z_(c)). Let us consider, for example, a casewhere a model eye of Gullstrand is used. In this case, the eyeballrotation center is regarded as being situated on the rear side by 13 mmalong the Z-axis from the corneal apex (see an eyeball model in FIG. 7).

As described above, the scheduled wearer S is instructed to facedirectly forward against the RGB-D camera 154-1; however, the head ofthe scheduled wearer does not necessarily face directly forward theRGB-D camera 154-1 during the photographing. The wording “face forwarddirectly” as used herein means a state in which the direction of thecoordinate system (the coordinate axis) of the RGB-D camera 154-1coincides with the direction of the coordinate system (the coordinateaxis) of the head of the scheduled wearer S.

In each of FIGS. 8A and 8B, the coordinate system of the RGB-D camera154-1 and the coordinate system of the head of the scheduled wearer Sare shown. As shown in each of FIGS. 8A and 8B, the coordinate system ofthe RGB-D camera 154-1 is defined as a coordinate system having theorigin equal to the optical center of the RGB-D camera 154-1, andhereafter the coordinate system is referred to as a “first cameracoordinate system”. The first camera coordinate system has the X axisextending in the horizontal direction of the RGB-D camera 154-1, the Yaxis (assigned a symbol “Ycc” in FIG. 8 for convenience of explanation)extending in the vertical direction of the RGB-D camera 154-1, and the Zaxis (a direction pointing to the frontward of the RGB-D camera 154-1 isa plus direction, and is assigned a symbol “Zcc” in FIG. 8 forconvenience of explanation) extending in the depth direction of theRGB-D camera 154-1. The coordinate system of the head of the scheduledwearer S is a coordinate system having the origin defined at apredetermined point in the head (e.g., a center of a nose), and ishereafter referred to as a “head coordinate system”. The head coordinatesystem has the X axis extending in the horizontal direction of the headof the scheduled wearer S, the Y axis (assigned a symbol “Yhh” in FIG. 8for convenience of explanation) extending in the vertical direction ofthe head, and Z axis extending in the depth direction of the head (adirection pointing to the depth side is a plus direction and is assigneda symbol “Zhh” in FIG. 8 for convenience of explanation).

Let us consider a case where the direction of the first cameracoordinate system does not coincide with the head coordinate system asshown in FIG. 8A. In this case, when the coordinate value equivalent to13 mm is added to the Z component of the corneal apex coordinate (x_(c),y_(c), z_(c)) in the first camera coordinate system, such addition ofthe coordinate value is divided into a Y component and a Z component inthe head coordinate system. Therefore, it is understood that eyeballrotation center coordinate ν_(rc1) cannot be calculated precisely. Inorder to precisely calculate the eyeball rotation center coordinateν_(rc1), at least it is necessary to let the direction of the firstcamera coordinate system coincide with the direction of the headcoordinate system. For this reason, in step S12 e, the processor 152 aestimates the position and the pose of the head of the scheduled wearerS based on the distance image obtained by the RGB-D camera 154-1. Forexample, by using the know technique described in non-patent document 3(Gabriele Fanelli, Juergen Gall, and Luc Van Gool: “Real Time Head PoseEstimation with Random Regression Forests” (2011)), it is possible toestimate the position and the pose of the head of the scheduled wearer Sbased on the distance image obtained by the RGB-D camera 154-1. Theposition is defined by three axes of XYZ, and the pose is defined by aroll angle, a yaw angle and a pitch angle.

Step S12 f in FIG. 6

The processor 152 a defines the head coordinate system based on theposition and pose of the head of the scheduled wearer S estimated instep S12 e in FIG. 6. By performing predetermined coordinate conversion,the processor 152 a converts the corneal apex coordinate (x_(c), y_(c),z_(c)) in the first camera coordinate system to the corneal apexcoordinate (x_(h), y_(h), z_(h)) in the head coordinate (see FIG. 8B).By executing step S12 f, a state where the scheduled wearer S pointsdirectly forward against the RGB-D camera 154-1 is attained in regard toprocessing on software.

Step S12 g in FIG. 6

By adding a default value a (a value corresponding to 13 mm in thisembodiment) to the Z component of the corneal apex coordinate (x_(h),y_(h), z_(h)) converted in step S12 f in FIG. 6, the processor 152 aobtains the eyeball rotation center coordinate ν_(rc1) (x_(h), y_(h),z_(h)+α). The eyeball rotation center coordinate ν_(rc1) (x_(h), y_(h),z_(h)+α) obtained here is an eyeball rotation center coordinate in agiven frame, and is a tentative value. It should be noted that thedefault value α is not limited to the value corresponding to 13 mm.Strictly speaking, the distance between the corneal apex and the eyeballrotation center is not uniquely defined when considering variousfactors, such as, a race, gender, age and visual acuity. Therefore, thedefault value a more suitable for the scheduled wearer S may be settableby selecting an appropriate default value a (an eyeball model)considering these factors.

Step S12 h in FIG. 6

Steps S12 a to S12 g of FIG. 6 are executed for each frame. In step S12h, the processor 152 a judges whether the tentative values of theeyeball rotation center coordinates ν_(rc1) (x_(h), y_(h), z_(h)+α)corresponding to a predetermined number of frames have been obtained byexecuting the steps S12 a to S12 g of FIG. 6 for a plurality of times.When the processor 152 a judges that the tentative values of the eyeballrotation center coordinates ν_(rc1) (x_(h), y_(h), z_(h)+α)corresponding to the predetermined number of frames have been obtained(S12 h: YES), the process proceeds to step S12 i in FIG. 6. When theprocessor 152 a judges that the tentative values of the eyeball rotationcenter coordinates ν_(rc1) (x_(h), y_(h), z_(h)+a) corresponding to thepredetermined number of frames have not been obtained (S12 h: NO), theprocess returns to step S12 a in FIG. 6 and steps S12 a to S12 g of FIG.6 are executed for a next frame.

Step S12 i in FIG. 6

The predetermined number of frames is sufficient for obtainingstatistics. Therefore, the processor 152 a calculates the average valueof the tentative values corresponding to the predetermined number offrames, and defines the calculated average value as the definitive valueof the eyeball rotation center coordinates ν_(rc1) (x_(h), y_(h),z_(h)+α).Thus, the eyeball rotation center coordinates ν_(rc1) (x_(h),y_(h), z_(h)+α) being the start point of the visual line is obtained.

S13 in FIG. 5 (Calculation Process for Visual Target Coordinate)

The scheduled wearer S is instructed to watch the visual target O duringphotographing. The scheduled wearer S may wear spectacle lenses whichthe scheduled wearer S usually wears. The visual target O is, forexample, an object which moves randomly or regularly, or an object whichappears or is arranged at a random position or a regular position. Theprocessor 152 a calculates the coordinate of the visual target O whichis the end point of the visual line of the scheduled wearer S. It shouldbe noted that the visual line information collected by the visual lineinformation collecting apparatus 150 is vector information of a visualline, and includes a vector length and a unit vector of the visual lineconnecting the eyeball rotation center (the start point of the visualline) with the visual target O (the end point of the visual line). FIG.9 is a flowchart illustrating in detail step S13.

Step S13 a in FIG. 9

The processor 152 a obtains the RGB image and the distance imagephotographed by the RGB-D camera 154-2 in step S11 (photographingprocess by RGB-D camera) in FIG. 5.

Step S13 b in FIG. 9

The processor 152 a detects the coordinate of the visual target O in theRGB image by analyzing the RGB image obtained by the RGB-D camera 154-2.For example, by using the known technique described in the non-patentdocument 2, the coordinate of the visual target O can be detected.

Step S13 c in FIG. 9

The processor 152 a identifies a pixel in the distance imagecorresponding to the coordinate (a pixel) detected in step S13 b in FIG.9. As a result, the three dimensional coordinate ν_(o1) of the visualtarget O is obtained.

Step S13 d in FIG. 9

As described above, the start point (the eyeball rotation center) andthe end point (the visual target) of the visual line are photographed bythe different RGB-D cameras. In this case, the coordinate system of theRGB-D camera 154-2 is defined as having the origin at the optical centerof the RGB-D camera 154-2, and is hereafter referred to as a “secondcamera coordinate system”. As in the case of the first camera coordinatesystem, the second camera coordinate system has the X axis extending inthe horizontal direction of the RGB-D camera 154-2, the Y axis extendingin the vertical direction of the RGB-D camera 154-2, and the Z axis (thedirection pointing to the front side of the RGB-D camera 154-2 is a plusdirection) extending in the depth direction of the RGB-D camera 154-2.

In order to calculate the visual line information based on the startpoint and the end point of the visual line photographed by the separateRGB-D cameras having the different coordinate systems, it is necessaryto convert the coordinate ν_(o2) of the visual target O in the secondcamera coordinate system to the coordinate ν_(o1) viewed from the firstcamera coordinate system, for example. When a rotation matrix and atranslation vector obtained from a relative relationship (a relationshipsuch as relative position or direction) of the first camera coordinatesystem viewed from the second camera coordinate system are defined asR₂₁ and t₂₁, respectively, and a time on a predetermined time axis isdefined as t, the above described conversion process is expressed by thefollowing equation:ν_(o1) ^(t) =R ₂₁ ^(t)(ν_(o2) ^(t) −t ₂₁ ^(t))

Let us consider, for example, a case where the relative positionalrelationship and the relative pose relationship between the RGB-D camera154-1 and the RGB-D camera 154-2 are known values by installing theRGB-D camera 154-1 and the RGB-D camera 154-2 using a jig or the like.In this case, the rotation matrix R₂₁ and the translation vector t₂₁ canbe treated as known parameters. Let us further consider a case where therelative positional relationship and the relative pose relationshipbetween the RGB-D camera 154-1 and the RGB-D camera 154-2 are unknown.In this case, the same characteristic point (e.g., a characteristicpoint on the face of the scheduled wearer S) is measured by the RGB-Dcamera 154-1 and the RGB-D camera 154-2, and the relative positionalrelationship and the relative pose relationship of the RGB-D camera154-1 and the RGB-D camera 154-2 are estimated based on the measuredsame characteristic point. It should be noted that since such estimationtechnique is known, detailed explanation thereof is omitted.

As described above, the coordinate system of the eyeball rotation centerof the scheduled wearer S photographed by the RGB-D camera 154-1 hasbeen converted to the head coordinate system. Therefore, the visualtarget O photographed by the RGB-D camera 154-2 should also be convertedto the head coordinate system after being converted to the coordinatevalue viewed from the first camera coordinate system as in the case ofthe eyeball rotation center. In this case, the scheduled wearer S alsomoves his/her heads as well as the visual line because the scheduledwearer S chases the visual target O with his/her eyes. Therefore, thehead coordinate system changes every second with respect to the firstcamera coordinate system. To chase change of the head coordinate system,the processor 152 a detects the position and pose of the head of thescheduled wearer S based on the distance image obtained by the RGB-Dcamera 154-1 at predetermined time intervals.

S13 f in FIG. 9

Each time the processor 152 a detects the position and pose of the headof the scheduled wearer S, the processor 152 a calculates the positiondifference and the pose difference of the head before and after thedetection. The processor 152 a updates the head coordinate system basedon the calculated position difference and the pose difference of thehead. By converting the first camera coordinate system to the updatedhead coordinate system, the processor 152 a converts the coordinateν_(o1) of the visual target viewed from the first camera coordinatesystem to the coordinate ν_(oh) of the visual target viewed from thehead coordinate system. In other words, the processor 152 a changes thecoordinate of the visual target O by an amount corresponding to theposition difference and the pose difference of the head before and afterthe detection so that the position and pose of the head is maintainedbefore and after the detection in regard to processing on software (sothat a state of pointing forward directly against the RGB-D camera 154-1is maintained).

Supplement of S13 (calculation process for visual target coordinate) inFIG. 5

The explanation about the flowchart in FIG. 9 is based on the premisethat the RGB-D camera 154-1 and the RGB-D camera 154-2 synchronouslyphotograph the subject (the scheduled wearer S and the visual target O).However, the photographing timings of the two RGB-D cameras do notnecessarily synchronized with each other on hardware. Therefore, byexecuting the following process, the photographing timings of the RGB-Dcamera 154-1 and the RGB-D camera 154-2 are synchronized with each otherin regard to processing on software.

FIG. 10 is a time chart illustrating asynchronous photographing timingof the two RGB-D cameras. As shown in FIG. 10, for example, thephotographing time t12 by the RGB-D camera 154-1 and the photographingtime t22 by the RGB-D camera 154-2 are asynchronous with each other. Theother corresponding photographing times are also asynchronous with eachother. The photographing time is meta data of the RGB image and thedistance image, and indicates a time at which the image is actuallyphotographed by each RGB-D camera.

Let us consider, for example, a case where the coordinate ν_(o2) of thevisual target O at the photographing time t22 is converted to thecoordinate ν_(oh) of the visual target viewed from the head coordinatesystem. In this case, the processor 152 a refers to the position andpose of the head of the scheduled wearer S at the photographing time t12and the time difference between the photographing time t12 and thephotographing time t22, and interpolates parameters of the position andpose of the head at the photographing time t22 by using an interpolationalgorithm, such as smoothing spline. The interpolated values areestimated values of the position and pose of the head at thephotographing time t22. The processor 152 a then calculates the headcoordinate system at the photographing time t22 from the estimatedvalues, and converts the coordinate v_(o1) of the visual target O at thephotographing time t22 to the coordinate ν_(o1), of the visual target Oviewed from the calculated head coordinate system. As a variation, thephotographing timings of the RGB-D camera 154-1 and the RGB-D camera154-2 may be synchronized by interpolating the coordinate ν_(o1) of thevisual target O at the photographing time t12.

S14 in FIG. 5 (Calculation Process for Visual Line Information)

The processor 152 a calculates the visual line vector having the eyeballrotation center coordinate ν_(rc1) (x_(h), y_(h), z_(h)+α) calculated instep S12 (calculation process of eyeball rotation center coordinate) inFIG. 5 as the start point and the coordinate v_(on) of the visual targetO calculated in step S13 (calculation process for visual targetcoordinate) in FIG. 5 as the end point. The processor 152 a stores thecalculated visual line information in a predetermined area in the memory152 b. The visual line information includes the time axis informationdefined when the visual line is oriented to the visual target O (e.g.,time information, specifically the photographing time by the RGB-Dcamera 154-1 and the RGB-D camera 154-2).

S15 in FIG. 5 (Termination Judgment Process)

The processor 152 a judges whether or not the visual line informationcorresponding to a predetermined time (a predetermined number of piecesof information) has been collected (stored) in the memory 152 b. Whenthe processor 152 a judges that the visual line informationcorresponding to the predetermined time has been collected (S15 in FIG.5: YES), the process of the flowchart is terminated. When the processor152 a judges that the visual line information corresponding to thepredetermined time has not been collected (S15 in FIG. 5: NO), theprocess returns to step S13 (calculation process for visual targetcoordinate) in FIG. 5.

After collecting the visual line information corresponding to thepredetermined time (after step S15: YES), the processor 152 a maydisplay information concerning the visual line information on themonitor 152 d. Various types of displaying manners for displayinginformation concerning the visual line information can be considered.For example, frequency of visual line passing points may be displayed onan image of a lens cut in a shape of a frame, for example, by contourlines, shading or dots.

According to the example 1, the start point of the visual line is set atthe eyeball rotation center which is equal to the origin defined fordesign of the spectacle lens. Therefore, an error in the direction anddistance of the visual line caused by a shift between the origin usedfor design of the spectacle lens and the start point of the visual linedoes not occur. Accordingly, the visual line information collectedaccording to the example 1 is suitable for use for design of thespectacle lens. Furthermore, according to the example 1, the scheduledwearer S is photographed by the RGB-D camera 154-1 placed before theeyes of the scheduled wearer S. Since the scheduled wearer S isphotographed largely in the RGB image, it is possible to detect the twodimensional position of the eye by the RGB image with a high degree ofaccuracy. Furthermore, since the RGB-D camera 154-1 and the scheduledwearer S are close to each other, it is possible to detect the positionof the eye in the depth direction with a high degree of accuracy. It isalso possible to detect the position and pose of the head of thescheduled wearer S with a high degree of accuracy. As described above,according to the example 1, since the position and pose of the eye andthe head of the scheduled wearer S can be detected with a high degree ofaccuracy, the calculation accuracy of the visual line is enhanced.Therefore, the visual line information which is advantageously used fordesign of spectacle lenses can be obtained.

Example 2 Configuration of Visual Line Information Collecting Apparatus150M

FIG. 11 is a block diagram illustrating a configuration of a visual lineinformation collecting apparatus 150M according to the example 2. Asshow in FIG. 11, the visual line information collecting apparatus 150Mincludes the information processing terminal 152 and the RGB-D camera154-1. That is, in contrast to the visual line information collectingapparatus 150 according to the example 1, the visual line informationcollecting apparatus 150M includes only one RGB-D camera. In the example2, explanations overlapping with those of the example 1 are omitted orsimplified for the sake simplicity. In the example 2, to configurationsand steps which are the same as those of the example 1, the samereference numbers are assigned and explanations thereof are omitted orsimplified.

FIG. 12 illustrates a use condition of the visual line informationcollecting apparatus 150M according to the example 2. FIG. 13 is aflowchart illustrating a visual line information collecting process bythe visual line information collecting apparatus 150M used in the usecondition shown in FIG. 12. As shown in FIG. 12, at a position fartherfrom the RGB-D camera 154-1 viewed from the scheduled wearer S and onthe rear side of the RGB-D camera 154-1, a chart sheet CH is installed.On the chart sheet CH, a plurality of visual targets O are printed atvarious positions.

Visual Line Information Collecting Process by Visual Line InformationCollecting Apparatus 150M

S111 in FIG. 13 (Photographing Process by RGB-D Camera)

The RGB-D camera 154-1 photographs an RGB image and a distance image ofthe scheduled wearer S at a predetermined frame rate.

S112 in FIG. 13 (Calculation Process of Eyeball Rotation CenterCoordinate) The processor 152 a calculates the coordinate ν_(rc1) of theeyeball rotation center which is the start point of the visual line ofthe scheduled wearer S. Since step S112 is the same as step S12(calculation process of eyeball rotation center coordinate) in FIG. 5,further explanation thereof is omitted.

S113 in FIG. 13 (Obtaining Process for Visual Target Coordinate)

During the photographing, the scheduled wearer S visually recognizeseach visual target O on the chart sheet CH in accordance with, forexample, voice guidance output from the information processing terminal152. The position of each visual target O on the chart sheet CH isknown, and the position information has been stored in the memory 152 bof the information processing terminal 152. The processor 152 a readsthe position information of the visual target O corresponding to thevoice guidance from the memory 152 b as the coordinate v₀₁ of the visualtarget O viewed from the first camera coordinate system, and, as in thecase of step S13 f in FIG. 9, converts the coordinate v_(oi) to thecoordinate v_(oh) of the visual target viewed from the head coordinatesystem.

S114 in FIG. 13 (Calculation Process for Visual Line Information)

The processor 152 a calculates the visual line vector (including avector length and a unit vector) having the eyeball rotation centercoordinate ν_(rc1) (x_(h), y_(h), z_(h)+α) calculated in step S112(calculation process of eyeball rotation center coordinate) in FIG. 13as the start point and the coordinate v_(oh) of the visual target Ocalculated in step S113 (obtaining process for visual target coordinate)in FIG. 13 as the end point. The processor stores the calculated visualline information in a predetermined area in the memory 152 b.

S115 in FIG. 13 (Termination Judgment Process)

By detecting the end of the voice guidance, the processor 152 a judgeswhether or not the scheduled wearer S has visually recognized all thevisual targets O on the chart sheet CH. When the processor 152 a judgesthat the scheduled wearer S has visually recognized all the visualtargets O on the chart sheet CH (S115: YES in FIG. 13), the processor152 a terminates the flowchart while judging that the visual lineinformation corresponding to the predetermined time has been collected.When the processor 152 a judges that there is a visual target O whichthe scheduled wearer S has not visually recognized yet (S115: NO in FIG.13), the process returns to step S113 (obtaining process for visualtarget coordinate) in FIG. 13 while judging that the visual lineinformation corresponding to the predetermined time has not beencollected.

As in the case of the example 1, according to the example 2, since thestart point of the visual line is set at the eyeball rotation centerwhich is equal to the origin for design of the spectacle lens, thevisual line information collected according to the example 2 is suitablefor use of design of the spectacle lens. Furthermore, as in the case ofthe example 1, according to the example 2, since the scheduled wearer Sis photographed by the RGB-D camera 154-1 placed before the eyes of thescheduled wearer S, the visual line information which is advantageouslyused for design of the spectacle lens can be obtained with a high degreeof accuracy. Furthermore, according to the example 2, since a singleRGD-B camera 154-1 is sufficient, cost for the visual line informationcollecting apparatus 150M can be reduced.

Variation 1 of Examples 1 and 2

In the examples 1 and 2, the three dimensional coordinate of the cornealapex is identified using the RGB-D camera. Specifically, in the examples1 and 2, a method, where the corneal apex coordinate (a pixel) isidentified using the RGB image by the camera 154 a, and then the threedimensional coordinate of the corneal apex is identified from the pixelin the distance image by the distance image photographing unit 154 bcorresponding to the pixel of the identified corneal apex, is used. Onthe other hand, in the variation 1, a corneal apex coordinate can bedirectly identified from a distance image without using an RGB image byapplying the technique described in non-patent document 4 (Tae Kyun Kim,Seok Cheol Kee and Sang Ryong Kim: “Real-Time Normalization and FeatureExtraction of 3D Face Data Using Curvature Characteristics”).Furthermore, regarding the visual target O, when an object having acharacteristic shape is used as the visual target, the coordinate of thevisual target O can be directly identified from the distance imagewithout using the RGB image by applying the technique described in thenon-patent document 4. Since, in the variation 1, it is possible toreplace the RGB-D camera with a distance image sensor, cost of thevisual line information collecting apparatus can be suppressed.

Variation 2 of Examples 1 and 2

In the example 1, a role of the RGB-D camera 154-1 after execution ofstep S12 (calculation process of eyeball rotation center coordinate) inFIG. 15 is limited to estimating the position and pose of the head ofthe scheduled wearer S. As in the case of the example 1, also in theexample 2, a role of the RGB-D camera 154-1 after execution of step S112(calculation process of eyeball rotation center coordinate) in FIG. 13is limited to estimating the position and pose of the head of thescheduled wearer S. For this reason, in the variation 2, after theeyeball rotation center coordinate is calculated in step S12 in FIG. 5or in step S112 in FIG. 13, the process executed by the RGB-D camera154-1 may be substituted by an IMU (Inertial Measurement Unit).Specifically, in the variation 2, the scheduled wearer S wears the IMUon the head. In the variation 2, steps after S13 (calculation processfor visual target coordinate) in FIG. 5 or steps after S113 (obtainingprocess for visual target coordinate) in FIG. 13 are executed using theposition and pose of the head measured by the IMU. It should be notedthat in this case the origin of the head coordinate system is set at thebarycenter of the IMU.

Example 3

In the following, the example 3 regarding a visual line informationcollecting process is explained. As explained in detail below, in theexample 3, wearing parameters are collected simultaneously and in serieswith the visual line information while considering the pose of the headof the scheduled wearer S. It should be noted that, in the example 3,explanations overlapping with those of the example 1 are omitted orsimplified. Furthermore, in the example 3, to configurations and stepswhich are substantially the same as those of the example 1, the samereference numbers are assigned and explanation thereof is omitted orsimplified.

FIG. 14 illustrates a use condition of a visual line informationcollecting apparatus 150N according to the example 3. Since theconfiguration of the visual line information collecting apparatus 150Nof the example 3 is the same as the configuration (FIG. 11) in theexample 2, explanation thereof is omitted. As shown in FIG. 14, thevisual line information collecting apparatus 150N according to theexample 3 includes the information processing apparatus 152 and theRGB-D camera 154-1, and the RGB-D camera 154-1 is installed on a tableso that the visual target O and the scheduled wearer S can bephotographed. That is, in the example 3, the visual line informationtaking into account the pose of the head and the wearing parameters areobtained by a single RGB-D camera. FIG. 15 is a flowchart illustrating avisual line information and wearing parameter collecting process by thevisual line information collecting apparatus 150N.

Visual Line Information and Wearing Parameter Collecting Process byVisual Line Information Collecting Apparatus 150N

FIG. 15 (Photographing Process by RGB-D Camera)

The RGB-D camera 154-1 photographs an RGB image and a distance image ofthe scheduled wearer S and the visual target O at a predetermined framerate. S512 in FIG. 15 (Calculation Process of Corneal Apex and EyeballRotation Center Coordinate)

The processor 152 a calculates the coordinate ν_(rc1) of the eyeballrotation center which is the start point of the visual line of thescheduled wearer S, and holds the calculated coordinate. Since step S512is similar to step S12 (calculation process of eyeball rotation centercoordinate) in FIG. 5, further explanation thereof is omitted. In stepS512, the corneal apex coordinate measured for obtaining the eyeballrotation center is also held. Specifically, since the corneal apexcoordinates are obtained for an amount corresponding to thepredetermined number of frames, the average of the obtained corneal apexcoordinates is determined and held as the corneal apex coordinate. Theheld corneal apex coordinate is used for calculating the wearingparameters in a later stage.

S513-1 in FIG. 15 (Obtaining Process for Visual Target Coordinate)

The scheduled wearer S is instructed to watch the visual target O duringthe photographing. In order to watch the visual target O, the scheduledwearer S may watch the visual target with the naked eyes or may usespectacle lenses which the scheduled wearer S usually wears. However,when, of the wearing parameters, one of a frame vertex distance, a framepantoscopic angle and a frame face form angle is calculated in stepS513-2, the scheduled wearer S is required to wear the spectacle lenses.The visual target O is, for example, an object which moves randomly orregularly, or an object which appears or is arranged at a randomposition or a regular position. The processor 152 a calculates thecoordinate of the visual target O which is the end point of the visualline of the scheduled wearer S. Since the obtaining process of thecoordinate of the visual target O is the same as step S13 in FIG. 5,explanation thereof is omitted.

S513-2 in FIG. 15 (Calculation Process of Wearing Parameter)

The processor 152 calculates the wearing parameters (a frame pantoscopicangle, a frame face form angle, a frame vertex distance and a pupillarydistance) (only a near working distance is calculated in S514). Detailsof the wearing parameters are explained below.

Calculation Process of Frame Pantoscopic Angle

FIG. 16 is a flowchart illustrating a frame pantoscopic anglecalculation process. In this process, frontal face three dimensionaldata of the scheduled wearer S defined based on the position and pose ofthe head obtained in step S513-1 in FIG. 15 and the corneal apexcoordinate (the corneal apex coordinate obtained in a state of notwearing the spectacle lenses) held in step S512 are used.

Step S501 a in FIG. 16

FIG. 17 is a transversal cross sectional view of the frontal face threedimensional data, and is used for explaining the frame pantoscopic anglecalculation process. FIG. 17 indicates the corneal apex coordinate V₁ aswell as the transversal cross section of the frontal face threedimensional data. The processor 152 a scans the pixels in the verticaldirection from the corneal apex coordinate V₁, and detects a point atwhich the Z coordinate value discontinuously changes rapidly as a framecharacteristic point. Through this scanning, the positions F₁ (x₁, y₁,z₁) and F₂ (x₂, y₂, z₂) shifted in the Z axis direction from the faceare detected as the frame characteristic points.

Step S501 b in FIG. 16

The processor 152 a calculates the frame pantoscopic angle using thepositions F₁ and F₂ of the frame characteristic points thus detected.The frame pantoscopic angle (θ) is expressed as follows.

$\left. {{frame}\mspace{14mu}{pantoscopic}\mspace{14mu}{angle}} \right) = {\tan^{- 1}\left( \frac{z_{2} - z_{1}}{y_{1} - y_{2}} \right)}$

Calculation Process for Frame Face Form Angle

FIG. 18 is a flowchart illustrating a frame face form angle calculationprocess. In this process, frontal face three dimensional data of thescheduled wearer S defined based on the position and pose of the headobtained in step S513-1 in FIG. 15 and the corneal apex coordinate heldin step S512 are used.

Step S502 a in FIG. 18

FIG. 19 is a top cross sectional view of the frontal face threedimensional data, and is used for explaining the frame face form anglecalculation process. FIG. 19 indicates the corneal apex coordinate V₁ aswell as the top cross section of the frontal face three dimensionaldata. The processor 152 a scans the pixels in the left and rightdirection from the corneal apex coordinate V₁, and detects a point atwhich the Z coordinate value discontinuously changes rapidly as a framecharacteristic point. Through this scanning, the positions F₃ (x₃, y₃,z₃) and F₄ (x₄, y₄, z₄) shifted in the Z axis direction from the faceare detected as the frame characteristic points.

Step S502 b in FIG. 18

The processor 152 a calculates the frame face form angle using thepositions F₃ and F₄ of the frame characteristic points thus detected.The frame face form angle (θ) is expressed as follows.

$\left. {{frame}\mspace{14mu}{face}\mspace{14mu}{form}\mspace{14mu}{angle}} \right) = {\tan^{- 1}\left( \frac{z_{3} - z_{4}}{x_{4} - x_{3}} \right)}$

Calculation Process for Frame Vertex Distance

FIG. 20 is a flowchart illustrating a frame vertex distance calculationprocess. In this process, frontal face three dimensional data of thescheduled wearer S defined based on the position and pose of the headobtained in step S513-1 in FIG. 15 and the corneal apex coordinate heldin step S512 are used.

Step S503 a in FIG. 20

FIG. 21 is a transversal cross sectional view of the frontal face threedimensional data, and is used for explaining the frame vertex distancecalculation process. FIG. 21 indicates the corneal apex coordinate V₁and the frame characteristic points F₁ and F₂, as well as thetransversal cross section of the frontal face three dimensional data. Asin the case of step S501 a in FIG. 16, the processor 152 a calculatesthe positions F₁ and F₂ of the frame characteristic points.

Step S503 b in FIG. 20

In FIG. 21, a line L₁ is a line drawn in parallel with the Z axis fromthe corneal apex V₁, and a line L2 is a line connecting the framecharacteristic points F₁ and F₂. The processor 152 a calculates thedistance between the corneal apex V₁ and an intersection of the line L₁and the line L₂ as the frame vertex distance.

Calculation Process of Pupillary Distance

FIG. 22 is a front view of the frontal face three dimensional data, andis used for explaining the pupillary distance calculation process. Theprocessor 152 a calculates the pupillary distance by calculating x₁₂-x₁₂along the X axis using the corneal apex positions ((x_(r2), y_(r2),z_(r2)) and (x₁₂, y₁₂, z₁₂)) of the left and right eyes obtained in stepS512 in FIG. 15.

S514 in FIG. 15 (Calculation Process for Visual Line Information) Theprocessor 152 a calculates the visual line vector having the eyeballrotation center coordinate ν_(rc1) (x_(h), y_(h), z_(h)+α) calculated instep S512 (calculation process of eyeball rotation center coordinate) inFIG. 15 as the start point and the coordinate v_(oh) of the visualtarget O calculated in step S513-1 (calculation process for visualtarget coordinate) in FIG. 15 as the end point. The processor 152 astores the calculated visual line information in a predetermined area inthe memory 152 b. The visual line information includes the time axisinformation defined when the visual line is oriented to the visualtarget O (e.g., time information, specifically the photographing time bythe RGB-D camera 154-1). Regarding the near working distance, the nearworking distance can be calculated by regarding the vector lengthdefined in a state where the visual target O is installed at a distancecorresponding to the near work of the scheduled wearer S as the nearworking distance.

S515 in FIG. 15 (Termination Judgment Process)

The processor 152 a judges whether or not the visual line informationcorresponding to a predetermined time (a predetermined number of piecesof information) has been collected (stored) in the memory 152 b. Whenthe processor 152 a judges that the visual line informationcorresponding to the predetermined time has been collected (S515 in FIG.15: YES), the process of the flowchart is terminated. When the processor152 a judges that the visual line information corresponding to thepredetermined time has not been collected (S515 in FIG. 15: NO), theprocess returns to step S513-1 (calculation process for visual targetcoordinate) in FIG. 15.

As in the case of the examples 1 and 2, according to the example 3, thestart point of the visual line is set at the eyeball rotation centerwhich is equal to the origin defined for design of the spectacle lens.Therefore, the visual line information collected according to theexample 3 is suitable for use for design of the spectacle lens.Furthermore, the visual line information (direction and distance) ismeasured continuously as time series data. Therefore, it is possible tojudge which part of the lens the scheduled wearer S uses with highfrequency, and thereby it becomes possible to give suitable aberrationdistribution to the lens based on the judged use frequency.

According to the example 3, the wearing parameters are obtainedsimultaneously and continuously as the time series data. Therefore, itbecomes possible to collect the wearing parameters with a high degree ofreliability by using an average or a median for the wearing parametersobtained as the time series data (there parameters are defined as truewearing parameters). According to the example 3, the visual lineinformation and the wearing parameters are obtained simultaneously andas time series data with a simple configuration as shown in FIG. 14 asan example. Furthermore, according to the example 3, the pose of thehead is considered for the calculation process of the wearingparameters. Therefore, accurate wearing parameters can be obtained.

The configuration of the visual line information collecting apparatus isnot limited to that shown in FIG. 14, but various types ofconfigurations may be used. For example, the configuration in which twoRGB-D cameras are used may also realize the same process as thatdescribed in the example 3.

Specific Design Method of Spectacle Lens by Spectacle Lens DesignComputer 202 Hereafter, a method for designing spectacle lenses usingthe visual line information collected according to the example 1 or 2 isexplained. FIG. 23 is a flowchart illustrating a progressive power lensdesign process by the spectacle lens design computer 202.

Design Example of Progressive Power Lens

S201 in FIG. 23 (Construction of Virtual Model)

The spectacle lens design computer 202 constructs a predeterminedvirtual model including an eyeball and a spectacle lens, assuming astate where the scheduled wearer S wears spectacle lenses. FIG. 24illustrates an example of the virtual model constructed by the spectaclelens design computer 202.

The eye axis length of an eyeball differs between myopia and hyperopia.For this reason, the spectacle lens design computer 202 has stored inadvance information indicating how the eye axis length differs dependingon degrees of myopia and hyperopia. From this information, the spectaclelens design computer 202 selects a suitable eyeball model E inaccordance with the prescription (spherical power, cylindrical power) ofthe scheduled wearer S contained in the received ordering data, anddisposes a selected eyeball model E in a virtual model space. An eyeballrotation center Eo is defined at the center of the eyeball model E.

The spectacle lens design computer 202 designs an initial spectacle lensmodel L while defining the eyeball rotation center Eo as the origin.Specifically, the spectacle lens design computer 202 determines theshape of each of the outer surface (the convex surface) and the innersurface (the concave surface) of the lens to be one of a sphericalsurface, an aspherical surface, a progressive surface and a free-formsurface (other than a progressive surface) based on the prescriptioncontained in the received ordering data. For example, in the case of aone side progressive power lens, the convex surface or the concavesurface is determined to be the progressive surface. The spectacle lensdesign computer 202 designs the initial spectacle lens model L bydetermining the center thickness based on the prescription, therefractive index of the lens and the like, and disposing the convexsurface and the concave surface while securing an interval correspondingto the determined center thickness.

Based on the wearing parameters measured trough the flowchart in FIG.15, the spectacle lens design computer 202 converts the measurements ofthe frame to lens arrange parameters, such as, a lens face form angle, alens pantoscopic angle, and a corneal vertex distance CVD. Suchconversion is performed using the measured wearing parameters, a shape,a rim and a groove position of a frame, a dioptric power, a base curve,a fitting point and a thickness of a lens, and the like. Based on theobtained lens face form angle, the lens pantoscopic angle, and thecorneal vertex distance CVD, the spectacle lens model L is disposed forthe eyeball model E. When the measurements of the wearing parameters arenot available, arbitrary values may be designated, and the lensarrangement parameters may be calculated from the designated values. Thecorneal vertex distance CVD is a distance between the rear vertex of thespectacle lens model L and the corneal apex of the eyeball model E. Thefitting point is determined depending on how long (mm) the pupil centershifts upward or downward from a datum line or how long (mm) the pupilcenter shifts upward from a lower rim of a frame when a half of a B sizein a box system defined in a JIS (Japanese Industrial Standard) isregarded as a reference line (the datum line). When the above describedvarious parameters are unknown, standard values may be used as the lensarrangement parameters. As an example, the corneal vertex distance CVDmay be a default value (e.g., 12.5 mm).

S202 in FIG. 23 (Obtaining of Visual Line Information)

The spectacle lens design computer 202 obtains the visual lineinformation collected according to the example 1 (or the example 2) fromthe visual line information collecting apparatus 150 (or 150M). Asdescribed above, the obtained visual line information includes theinformation concerning the visual line vector, such as the vector lengthand a unit vector, and the time axis information when the visual line isoriented to the visual target O.

S203 in FIG. 23 (Calculation of Use Region and Use Frequency)

The spectacle lens design computer 202 calculates a use region (a regionthrough which a visual line passes) on the spectacle lens model L andthe use frequency in the region by the scheduled wearer S based on thevisual line information. Specifically, the spectacle lens designcomputer 202 calculates an intersection between the unit vector (thedirection of the visual line) of each visual line information having theorigin at the eyeball rotation center Eo and the spectacle lens model L(e.g., the convex surface), and determines the use region from thedistribution of the calculated intersections. Based on the unit vectorand the time axis information of each visual line information, thespectacle lens design computer 202 calculates a time for which eachvisual line stays at each point in the use region, and determines theuse frequency in the region from the calculated staying time at eachpoint.

S204 in FIG. 23 (Setting of Principal Meridian)

The spectacle lens design computer 202 calculates a position (a point)at which the use frequency becomes high on the spectacle lens model Lbased on the use region and the use frequency calculated in step S203(calculation of use region and use frequency) in FIG. 23, and draws aprincipal meridian on the spectacle lens model L by smoothly connectingneighboring calculated points with, for example, spline interpolation.The spectacle lens design computer 202 sets addition power distributionon the principal meridian based on the vector length (the distanceinformation of the visual line) of each visual line information passingthrough the principal meridian drawn on the spectacle lens model. Theaddition power distribution is obtained, for example, by arranging aplurality of control points on the principal meridian, calculating therefractive power at each control point based on the vector length of thevisual line information passing through each control point, andinterpolating the refractive powers of the neighboring control pointswith, for example, spline interpolation, such as B-spline.

S205 in FIG. 23 (Control for Prismatic Effect in Horizontal Direction)

The spectacle lens design computer 202 defines a plurality of crosssectional curves extending in the horizontal direction from theprincipal meridian set in step S204 (setting of principal meridian) inFIG. 23, and sets refractive power distribution on each cross sectionalcurve according to the dioptric power distribution of each of a distanceportion, a progressive power zone and a near portion.

S206 in FIG. 23 (Tentative Determination of Lens Surface Shape)

The spectacle lens design computer 202 tentatively determines ageometrical shape of a lens surface of the spectacle lens model L bysmoothly connecting the refractive power distribution on the principalmeridian and on each cross sectional curve extending in the horizontaldirection, for example, using spline interpolation, and by convertingthe connected refractive power distribution into curvature distributionby a known conversion equation.

S207 in FIG. 23 (Ray Tracing Calculation)

The spectacle lens design computer 202 executes optimization calculationby ray tracing with respect to the tentatively determined spectacle lensmodel L, and thereby evaluates the use region calculated in step S203(calculation of use region and use frequency) in FIG. 23. An evaluationvalue and an evaluation function defining a predetermined convergencecondition for optimizing the use region may be arbitrarily set.

S208 in FIG. 23 (Judgment on Satisfaction of Convergence Condition)

The spectacle lens design computer 202 judges whether or not thepredetermined convergence condition is satisfied based on evaluationresults in step S207 (ray tracing calculation) in FIG. 23. When thespectacle lens design computer 202 judges that the predeterminedconvergence condition is not satisfied (S208 in FIG. 23: NO), theprocess proceeds to step S209 (fine adjustment of addition powerdistribution) in FIG. 23.

S209 in FIG. 23 (Fine Adjustment of Addition Power Distribution)

The spectacle lens design computer 202 makes fine adjustment to theaddition power distribution by modifying the position and the refractivepower of each control point on the principal meridian of the spectaclelens model so that the predetermined convergence condition is satisfied.

S210 in FIG. 23 (Control for Prismatic Effect in Horizontal Direction)

After the fine adjustment of the addition power distribution in stepS209 (fine adjustment of addition power distribution) in FIG. 23, as inthe case of step S205 (control for prismatic effect in horizontaldirection) in FIG. 23, the spectacle lens design computer 202 defines aplurality of cross sectional curves extending in the horizontaldirection from the principal meridian, and sets refractive powerdistribution on each cross sectional curve according to the dioptricpower distribution of each of a distance portion, a progressive powerzone and a near portion. Then, the spectacle lens design computer 202causes the process of the flowchart to return to step S206 (tentativedetermination of lens surface shape) in FIG. 23.

Let us consider, for example, a case where it is judged in step S208(judgment on satisfaction of convergence condition) in FIG. 23 that thepredetermined convergence condition is satisfied (S208 in FIG. 23: YES)as a result of correction of the lens surface shape by repeating stepsfrom S206 (tentative determination of lens surface shape) in FIG. 23 tostep S210 (control for prismatic effect in horizontal direction) in FIG.23. In this case, the spectacle lens design computer 202 calculates anaspherical surface correction amount according to the wearing condition(e.g., the lens pantoscopic angle and the lens face form angle), andadds the calculated aspherical surface correction amount to thetentative lens surface shape after step S206 (tentative determination oflens surface shape) in FIG. 23. As a result, the lens surface shape isdetermined, and the shape design of the progressive power lens iscompleted.

According to the design process, a progressive power lens which hassuitable aberration distribution for an actual use condition and issuitable for use of each visual line and the visual distance by thescheduled wearer S can be designed.

Hereafter, two design examples (design examples 1 to 2) designed whendifferent convergence conditions are used are explained.

Design Example 1

FIG. 25A shows transmission astigmatism distribution of a lens beforeoptimization according to the design example 1, and FIG. 25B showstransmission astigmatism distribution of a lens after optimizationaccording to the design example 1. In the design example 1, theevaluation function is defined such that the transmission astigmatismbecomes lower than or equal to 2.0 diopter (2.0D) within the use region(a region surrounded by an ellipse in FIGS. 25A and 25B) calculated instep S203 (calculation of use region and use frequency) in FIG. 23. Asshown in FIG. 25B, since the transmission astigmatism is suppressed to avalue lower than or equal to 2.0D in the use region, shake anddistortion in the use region are reduced.

Design Example 2

FIG. 26A shows distribution of logMAR visual acuity before optimizationaccording to the design example 2, and FIG. 26B shows distribution oflogMAR visual acuity after optimization according to the design example2. Details about logMAR visual acuity can be seen, for example, inJapanese Patent Publication No. 4033344B. In the design example 2, theevaluation function is defined such that, within the use region in adistance portion situated on an upper side of the fitting point FP onthe lens, an area in which the logMAR visual acuity becomes lower thanor equal to 0.155 (0.7 or more in terms of decimal visual acuity)becomes larger than 190 mm² on the basis of an area on the distributiondiagram (not on the basis of an area on the lens). As shown in FIG. 26B,in the design example 2, assuming a situation where a far point ismainly viewed, for example, during car driving, a wide range in whichthe scheduled wearer S can clearly recognize an object within the useregion in the distance portion can be secured.

Five design examples (design examples 3-1 to 3-3 and design examples 4-1to 4-2) of a progressive power lens using the visual line informationaccording to the embodiment are explained. The design examples 3-1 to3-3 relate to setting of an inside-shift amount of the principalmeridian, and the design examples 4-1 to 4-2 relate to setting of anaddition power curve.

Design Example 3-1

There is a case where a face of a person (the scheduled wearer S) isinclined even when the person thinks that he or she faces frontward. Insuch a case, even when a lens does not have a face form angle, the lensis apparently inclined with respect to the frontward visual line. Tocompare these situations, FIG. 27A shows a case where the face is notinclined, and FIG. 27B shows a case where the face is inclined. In eachof these drawings, a top cross sectional view in a lens-worn state isillustrated on the upper side together with the head coordinate system,and a passing point of the frontward visual line on the lens isillustrated on the lower side.

In the state where the face is not inclined (FIG. 27A), the frontwardvisual lines pass through set positions P_(R) and P_(L) of the assumedpupillary distance. On the other hand, in the state where the face isinclined (FIG. 27B) (it is assumed that the head is inclined about theY-axis by 10 degrees as an example), the actual frontward visual linesdo not pass through the set positions P_(R) and P_(L) of the assumedpupillary distance, but pass through positions Q_(R) and Q_(L) which areshifted from the set positions P_(R) and P_(L). That is, the state shownin FIG. 27B corresponds to a state where the frame face form angle of 10degrees is apparently added to the frontward visual lines.

In this design example, the prism correction and the aberrationcorrection according to the apparent face from angle is applied to thedesign.

FIG. 28 is a diagram for explaining the comparison between aconventional design example (correction for the apparent face form angleis not executed) and the above described design example (correction(prism correction and aberration correction) according to the apparentface form angle). In this case, the calculation is made using S+3.00,ADD2.50D. Specifically, in FIG. 28, for each of the conventional designand the subject design example, the difference in average transmissiondioptric power (on the basis of a convex surface coordinate of the rightlens, the difference along the cross section at Y=0 mm, ±20 mm rangealong X-axis) with respect to reference design is graphically shown. InFIG. 28, a curve indicated by a dashed line represents the difference inaverage transmission dioptric power between the conventional design andthe reference design, and a curve indicated by a solid line representsthe difference in average transmission dioprtic power between thesubject design example and the reference design.

As shown in FIG. 28, in the conventional design, the difference withrespect to the reference design becomes larger than or equal to 0.3D. Bycontrast, according to the subject design example, the difference withrespect to the reference design is suppressed to a value smaller than orequal to 0.1D.

Design Example 3-2

There is a case where the difference is caused between actual visualline passing points and the pupillary distance PD assumed for the lensdue to a measurement error of the pupillary distance PD. The subjectdesign is an example for dealing with the above described case. FIG. 29is an explanatory illustration for explaining the subject design underthe situation. Here, we assume that the actual visual line shifts by 1mm to the nose side with respect to the pupillary distance PD measuredfor the right eye. In such a situation, in the conventional design,since the lens deviates from the position of the frontward visual line,the measured pupillary distance PD also shifts and thereby the visualline for viewing a range of an intermediate point to a near point passesa position in a region where the astigmatism exists (see a visual linepassing position indicated by a dashed line on the astigmatism diagramshown in FIG. 29).

On the other hand, as described above, since, according to theembodiment, the staying time information concerning the passing positionof the visual line on the lens can be obtained, the pupillary distancePD can be altered according to the staying time information. Therefore,it becomes possible to cause the visual line for viewing a range of anintermediate point to a near point to pass through a position where theastigmatism is small.

FIG. 30 illustrates the difference between the conventional design andthe subject design in the above described situation. In this case, thecalculation is made using S+0.00D, ADD2.50D. Specifically, FIG. 30 is agraph of the transmission astigmatism (on the basis of the convexsurface coordinate) illustrating the comparison between the conventionaldesign and the subject design. As shown in FIG. 30, in the case of theconventional design, the curve indicated by the dashed line in FIG. 29becomes the principal meridian, and there is a difference at the maximumof 0.4D between the conventional design and the subject design where thepupillary distance PD is modified.

Design Example 3-3

In the case where the eye points EP differ between the left and theright and thereby fitting points FP differ, if the downward rotationamount is the same for the left and the right, there is a possibilitythat the height and the inside-shift amount of the visual line passingposition defined when a near point is viewed differ between the left andthe right. Therefore, the height and the inside-shift amount need to bemodified. FIG. 31A is an explanatory illustration for explaining such asituation. In this case, an example where the left FP is higher by 2 mmthan the right FP is illustrated. As shown in FIG. 31A, regarding theleft eye, the actual visual line passing position for the near visionshifts from PL to QL, and the inside-shift amount of the visual linealso differs (in FIG. 31A, the actual visual line position is indicatedby a curve of a solid line).

FIG. 31B is a graph illustrating an addition power curve, in which acurve indicated by a dashed line represents the addition power in thecase of the conventional design, and a curve indicated by a solid linerepresents the addition power in the case of the subject design example.As shown in FIG. 31B, in the case of the conventional design, theaddition power of 2.50D is obtained at the position P_(R) of the righteye; however, only 2.36D is obtained at the position Q_(L) of the lefteye.

By contrast, according to the subject design example, the addition powerof 2.50D can be secured at the position Q_(L) by adjusting the additionpower on the principal meridian from the visual line information.

Design Example 4-1

In the subject design example, an addition power curve is set from thenear distance and the distance information on the fitting point FPaccording to the embodiment. For example, it is assumed that the orderedprescription is S0.00, ADD2.50D (40 cm in terms of the distance). Since,by the measurement, the distance information at the fitting pint FP is1.7 m (corresponding to approximately 0.6D) and the near distance is 45cm, the addition power of approximately 2.22D is sufficient andtherefore the design is made in the condition of ADD2.22. That is,according to the subject design, S0.00D and ADD2.22D are used.

FIG. 32 is a graph illustrating an addition power curve according to thesubject design example (a curve indicated by a solid line in FIG. 32),In FIG. 32, a graph illustrating an addition power curve according tothe conventional design is also shown for comparison (a curve indicatedby a dashed line in FIG. 32). As can be seen from FIG. 32, regarding thenear distance, setting is made at a nearer distance than an actuallyused distance in the conventional design. Therefore, according to theconventional design, a wearer is conversely required to approach anobject for near vision. Furthermore, in the conventional design, changein the addition power is large, and therefore the astigmatism becomesalso large. As a result, an intermediate portion becomes narrow.

FIG. 33A illustrates transmission astigmatism according to theconventional design, and FIG. 33B illustrates transmission astigmatismaccording to the subject design. FIGS. 33A and 33B are based on a convexsurface coordinate of a right lens, the range of Y-axis of ±20 mm, andthe pitch of 5 mm As can be seen from FIG. 33, according to theconventional design, unnecessarily large addition power is added, andthereby the astigmatism becomes large. On the other hand, according tothe subject design example, the addition power curve on the principalmeridian can be designed such that a sufficient amount of addition powercan be provided at the visual line passing position for near vision, andtherefore the astigmatism can be reduced. Furthermore, according to thesubject design example, the minimum value of the aberration is decreasedand encroaching of the aberration is also suppressed, and as a result awide intermediate portion can be secured. It should be noted that thetransmission astigmatism diagram represents the astigmatism on areference sphere having a radius defined from the eyeball rotationcenter to the vertex of the rear surface of the lens, and a light rayproceeds from an object and passes through the lens and the eyeballrotation center.

FIG. 34 is a graph illustrating the difference in transmissionastigmatism (on the basis of the convex surface coordinate of the rightlens) between the subject design example and the conventional design.Specifically, the graph represents the difference in astigmatism in across sectional direction at Y=−5 mm, X=±20 mm. As can be seen from FIG.34, the difference in astigmatism between the subject design example andthe conventional design at Y=−5 mm, X=±20 mm is larger than or equal to0.25D at most, and therefore it is understood that the subject designexample is advantageous.

Design Example 4-2

The subject design example is an example where an addition power curveis set by considering the fitting point FP according to the embodimentand by further considering the distance information of a visual line fordistance vision on the upper side of the fitting point FP. For example,it is assumed the ordered prescription is S0.00D, ADD2.50D. When themeasured distance information of the visual line for distance vision isa finite distance (it is assumed that the distance is 2 m, for example),the design can be made by defining the dioptric power for distancevision as a value obtained by adding a dioptric power corresponding tothe measured distance information to the ordered prescription. At apoint for near vision, an addition power curve is set by converting thedistance information into a dioptric power and by considering thedioptric power for distance vision obtained as above. For example, thedesign is made by (the dioptric power at a position for nearvision)=(added infinite distance)+(change in addition power).

FIG. 35 is a graph illustrating an addition power curve according to thesubject design example (a curve indicated by a solid line in FIG. 35).In FIG. 35, a graph illustrating an addition power curve according tothe conventional design is also shown for comparison (a curve indicatedby a dashed line in FIG. 35). As can be seen from FIG. 35, regardingdistance vision, setting is made at a father distance than an actuallyused distance, accommodation is needed accordingly, and thereby thewearer may be fatigued. Furthermore, in the conventional design, changein the addition power is large, the astigmatism becomes larger, andthereby the size of the intermediate portion is reduced.

FIG. 36A illustrates the transmission astigmatism according to theconventional design (design by the ordered prescription is S0.00,ADD2.50D), and FIG. 36B illustrates the transmission astigmatismaccording to the subject design example (design in the condition ofS0.50D, ADD2.00D). FIGS. 36A and 36B are based on a convex surfacecoordinate of a right lens, the range of Y-axis of ±20 mm, and the pitchof 5 mm. As can be seen from FIGS. 36A and 36B, according to the subjectdesign example, since the dioptric power corresponding to the requireddistance (i.e., the measured distance) is added to the dioptric powerfor distance vision, a required dioptric power for near vision can beachieved at the visual line passing position for near vision even if theprescribed addition power is reduced. As a result, there is no necessityto add an extra addition power, and thereby it becomes possible tosuppress the astigmatism. Furthermore, according to the subject designexample, the maximum value of the aberration is decreased, encroachingof the aberration is also suppressed, and as a result a wideintermediate portion can be secured.

FIG. 37 is a graph illustrating the difference in transmissionastigmatism (on the basis of the convex surface coordinate of the rightlens) between the subject design example and the conventional design.Specifically, the graph represents the difference in astigmatism in across sectional direction at Y=−5 mm, X=±20 mm. As can be seen from FIG.37, the difference in astigmatism between the subject design example andthe conventional design at Y=−5 mm, X=±20 mm is larger than or equal to0.45D at most, and therefore it is understood that the subject designexample is advantageous.

The transmission average dioptric power and the transmission astigmatismrespectively represent an average dioptric power error and astigmatismcaused on a sphere (the rear vertex sphere, V in FIG. 24) having aradius equal to a distance from the eyeball rotation center to the rearvertex of the lens defined for a right ray passing through the convexsurface and the concave surface of the lens and further passing throughthe eyeball rotation center.

Design Example of Single-Vision Lens

FIG. 38 is a flowchart illustrating a design process for a single-visionlens by the spectacle lens design computer 202.

S301 (Construction of Virtual Model) to S303 (Calculation of Use Regionand Use Frequency) in FIG. 38

The spectacle lens design computer 202 executes steps S301 (constructionof virtual model), S302 (obtaining of visual line information) and S303(calculation of use region and use frequency) in FIG. 38. An initialspectacle lens model L of the subject design example is, for example, aspherical lens having a spherical shape selected based on theprescription. Since these steps are similar to step S201 (constructionof virtual model), S202 (obtaining of visual line information) and S203(calculation of use region and use frequency) in FIG. 23, specificexplanation thereof is omitted.

S304 in FIG. 38 (Initial Setting, such as, Aspherical Coefficient)

The spectacle lens design computer 202 sets initial values of parametersconcerning the aspherical coefficient and a free-form surface based onthe initial spectacle lens model L in accordance with the use region andthe use frequency calculated in step S303 (calculation of use region anduse frequency) in FIG. 38.

S305 in FIG. 38 (Tentative Determination of Lens Surface Shape)

The spectacle lens design computer 202 tentatively determines ageometrical shape of a lens surface of the spectacle lens model L basedon the parameters concerning the aspherical surface coefficient and thefree-from surface.

S306 in FIG. 38 (Ray Tracing Calculation)

The spectacle lens design computer 202 executes optimization calculationby ray tracing with respect to the tentatively determined spectacle lensmodel L, and thereby evaluates the use region calculated in step S303(calculation of use region and use frequency) in FIG. 38.

S307 in FIG. 38 (Judgment on Satisfaction of Convergence Condition)

The spectacle lens design computer 202 judges whether or not thepredetermined convergence condition is satisfied based on evaluationresults in step S306 (ray tracing calculation) in FIG. 38. When thespectacle lens design computer 202 judges that the predeterminedconvergence condition is not satisfied (S307 in FIG. 38: NO), theprocess proceeds to step S308 (change of aspherical coefficient andetc.) in FIG. 38,

S308 in FIG. 38 (Change of Aspherical Coefficient and Etc.)

The spectacle lens design computer 202 changes the parameters concerningthe aspherical coefficient and the free-form surface so that thepredetermined convergence condition is satisfied. Then, the spectaclelens design computer 202 controls the process of the flowchart to returnto step S305 (tentative determination of lens surface shape) in FIG. 38.

For example, let us consider a case where it is judged that thepredetermined convergence condition is satisfied (S307 in FIG. 38: YES)as a result of correction of the lens surface shape by repeating stepsfrom S305 (tentative determination of lens surface shape) in

FIG. 38 to S308 (change of aspherical coefficient and etc.) in FIG. 38.In this case, the spectacle lens design computer 202 calculates anaspherical surface correction amount according to the wearing condition(e.g., a lens pantoscopic angle, a lens face form angle), and adds theaspherical surface correction amount to the tentative lens surface shapeafter execution of step S305 (tentative determination of lens surfaceshape) in FIG. 38. As a result, the lens surface shape is determined,and the shape design of the single-vision lens is completed.

According to the subject design process, the single-vision lens whichhas suitable aberration distribution for an actual use condition and issuitable for use of each visual line and the visual distance by thescheduled wearer S can be designed.

In the foregoing, an example where a progressive power lens or asingle-vision lens is designed using the visual line information of thescheduled wearer S; however, in another embodiment, a spectacle lensmost suitable for the condition corresponding to the visual lineinformation of the scheduled wearer S may be selected from a pluralityof types of preset spectacle lenses.

The spectacle lens design computer 202 may display, on the monitor 152 dthrough the host computer 200 and via the Internet, informationconcerning the transmission astigmatism distribution, the transmissionaverage dioptric power distribution, the logMAR visual acuitydistribution of the designed lens, a performance index described inpatent document 2 (Japanese Patent Publication No. 3919097B), an RGBimage obtained by the photographing apparatus or another RGB image, adiagram in which image processing is executed for each pixel accordingto aberration of a light ray with respect to a three-dimensional virtualobject image, and an image in which the frequency of the visual linepassing points are superimposed on the above described information ascontour lines, shading, dots, etc. Such representation may be performedby superimposing an image of a lens cut in a shape of a frame on theimage of the above described distribution diagram, the RGB image or thethree dimensional virtual image. Examples of such displayed images areillustrated in FIGS. 39A and 39B. Each of FIGS. 39A and 39Bschematically illustrates an image in which a design result, a frame andthe visual line information are arranged to overlap with each other, andrepresents the distribution of the logMAR as a result of design shown inFIG. 26. Specifically, FIG. 39A illustrates a case where the visual linestaying time and the passing position are represented by contour lines,and FIG. 39B is a case where the visual line passing points are plotted.

The foregoing is the explanation about the embodiment of the invention.Embodiments according to the invention are not limited to the abovedescribed examples, and various types of variations can be made withinthe scope of the technical concept of the invention. For example,embodiments may include examples and variations described herein by wayof illustration or modifications thereof combined in an appropriatemanner.

What is claimed is:
 1. A spectacle lens design system, comprising: aneyeball rotation center determination unit configured to identify acorneal apex position of an eye of a subject based on an imagephotographed by a predetermined photographing apparatus and determine aneyeball rotation center position of the subject based on the identifiedcorneal apex position; a visual line information calculation unitconfigured to calculate visual line information of the subject definedwhen the subject watches a visual target disposed at a predeterminedposition, based on the eyeball rotation center position determined bythe eyeball rotation center determination unit and the position of thevisual target; and a shape design unit configured to design a shape of aspectacle lens based on predetermined prescription information and thevisual line information calculated by the visual line informationcalculation unit.
 2. The spectacle lens design system according to claim1, further comprising a wearing parameter calculation unit configured tocalculate a wearing parameter based on the corneal apex position of theeye identified based on the image photographed by the predeterminedphotographing apparatus, wherein the shape design unit designs the shapeof the spectacle lens using the wearing parameter calculated by thewearing parameter calculation unit.
 3. The spectacle lens design systemaccording to claim 2, wherein the wearing parameter includes at leastone of a frame pantoscopic angle, a frame face form angle, a framevertex distance, a pupillary distance and a near working distance. 4.The spectacle lens design system according to claim 2, wherein thewearing parameter calculation unit continuously calculates wearingparameter values as time series data, and determines a true wearingparameter by using the wearing parameter values calculated continuouslyas the time series data.
 5. The spectacle lens design system accordingto claim 1, wherein: when a coordinate system whose origin is equal to areference point set at the predetermined photographing apparatus isdefined as a photographing apparatus coordinate system, and a coordinatesystem whose origin is equal to a reference point set at a head of thesubject is defined as a head coordinate system, the eyeball rotationcenter determination unit operates to: calculate a position and a poseof the head of the subject in the photographing apparatus coordinatesystem based on the image photographed by the predeterminedphotographing apparatus; define the head coordinate system based on thecalculated position and the pose of the head of the subject; convert acoordinate of the corneal apex position in the photographing apparatuscoordinate system to the corneal apex position in the head coordinatesystem by making directions of coordinate axes of the defined headcoordinate system and directions of coordinate axes of the definedphotographing apparatus coordinate system coincide with each other byperforming a predetermined coordinate conversion; and obtain acoordinate of a position of the eyeball rotation center by adding adefault value to the coordinate of the corneal apex position in theconverted head coordinate system.
 6. The spectacle lens design systemaccording to claim 5, further comprising: a detection unit configured todetect, at predetermined time intervals, the position and the pose ofthe head based on the image photographed by the predeterminedphotographing apparatus or detected data by a detecting apparatuscapable of detecting the position and the pose of the head of thesubject; and a pseudo moving unit configured to move, at predeterminedtime intervals, the position of the visual target, in a pseudo manner,by an amount corresponding to a difference of the position of the headbefore and after detection by the detection unit and a difference of thepose of the head before and after detection by the detection unit sothat the position and the pose of the head of the subject is maintained,in the pseudo manner, before and after the detection, wherein the visualline information calculation unit calculates the visual line informationbased on the determined eyeball rotation center position and theposition of the visual target moved in the pseudo manner.
 7. Thespectacle lens design system according to claim 1, wherein: the image isphotographed by the predetermined photographing apparatus at apredetermined frame rate; and in the eyeball rotation centerdetermination unit, tentative positions of the eyeball rotation centerare calculated for a predetermined number of frame images by determiningeyeball rotation center positions for a predetermined number of frames,and a true eyeball rotation center position is determined based on thecalculated tentative positions in the predetermined number of frameimages.
 8. The spectacle lens design system according to claim 1,wherein the visual line information is vector information of a visualline including a vector length and a unit vector of a visual lineconnecting the eyeball rotation center position with the position of thevisual target.
 9. The spectacle lens design system according to claim 8,wherein the visual line information further includes time axisinformation of a visual line.
 10. The spectacle lens design systemaccording to claim 9, further comprising: a tentative shape design unitconfigured to design a tentative shape of the spectacle lens based onpredetermined prescription information; a use calculation unitconfigured to calculate a position on a spectacle lens through which avisual line defined when the subject wears a spectacle lens having thetentative shape passes, and a staying time of the visual line at thecalculated position on the spectacle lens, based on the vector length,the unit vector and the time axis information of the visual lineincluded in the visual line information calculated by the visual lineinformation calculation unit, and thereby to calculate a use region anda use frequency in the spectacle lens by the subject; and a correctionunit that corrects the tentative shape based on the calculated useregion and the use frequency.
 11. The spectacle lens design systemaccording to claim 1, further comprising a visual line informationdisplaying unit configured to display, information concerning thecalculated visual line information.
 12. A spectacle lens supply system,comprising: a spectacle lens design system according to claim 1; and aspectacle lens manufacturing apparatus configured to manufacturespectacle lenses using the designed shape of the spectacle lens createdby the spectacle lens design system.
 13. A spectacle lens design method,comprising: photographing a subject with a predetermined photographingapparatus; identifying corneal apex position of an eye of the subjectbased on an image photographed with the predetermined photographingapparatus; determining an eyeball rotation center position of thesubject based on the identified corneal apex position; calculatingvisual line information of the subject defined when the subject watchesa visual target disposed at a predetermined position, based on theeyeball rotation center position and the position of the visual target;and designing a shape of a spectacle lens based on predeterminedprescription information and the visual line information.
 14. Thespectacle lens design method according to claim 13, further comprising:calculating a wearing parameter based on the corneal apex position ofthe eye identified based on the image photographed by the predeterminedphotographing apparatus, wherein the shape of the spectacle lens isdesigned using the calculated wearing parameter.
 15. The spectacle lensdesign method according to claim 14, wherein the wearing parameterincludes at least one of a frame pantoscopic angle, a frame face formangle, a frame vertex distance, a pupillary distance and a near workingdistance.
 16. The spectacle lens design system according to claim 14,wherein wearing parameter values are continuously calculated as timeseries data, and a true wearing parameter is determined by using thewearing parameter values calculated continuously as the time seriesdata.
 17. A spectacle lens manufacturing method, comprising: a spectaclelens manufacturing process of manufacturing the spectacle lens based onthe shape of the spectacle lens designed by the design method accordingto claim 13.